Amorphous clay materials of towada ando soils

Towada Ando soils consisted of five soils—Towada-a (1,000 years old), Towada-b (2,000 years old), Chuseri (4,000 years old), Nanbu (8,600 years old), and Ninokura soils (10,000 years Amorphous clay materials of these soils taken at different localities were studied by the combined use of selective dissolution and differential infrared spectroscopy, X-ray analysis, electron microscopy, etc.

The main clay minerals of Towada-a soils, present-day soils, were montmorillonite-vermic-ulite chloritic intergrades and opaline silica, or these minerals and allophane in the humus horizons, and allophane in the non-humus ones. Towada-b soils overlain by the Towada-a soils showed the clay mineralogical constituents similar to those of Towada-a soils. However, allophane was one of the main clay minerals in all the humus horizons as well as non-humus ones. The main clay minerals of Chuseri soils were allophane and layer silicates consisting chiefly of chloritic intergrades and chlorite in the humus horizons, and allophane in the non-humus ones. Opaline silica was present in minor amounts in the humus horizons of Chuseri soils, but nearly absent in Nanbu and Ninokura soils.

There were remarkable differences in the clay mineralogical composition of Nanbu and Ninokura soils with differences of their environmental conditions. Allophane and imogolite Were dominant in the clay fractions of both humus and non-humus horizons of very shallowly buried Nanbu soil which was subjected to the strong leaching process. Allophane was the main clay mineral of deeply buried Nanbu and Ninokura soils which showed the absence of notable accumulation of bases and silica. On the contrary, halloysite with a small amount of siliceous amorphous material appeared in very deeply buried Nanbu and Ninokura soils where bases and silica were distinctly accumulated. The amounts of halloysite in the clay fractions were larger in the humus horizons than non-humus ones, and in Ninokura soil than Nanbu soil.

Soil age, soil organic matter, and depositional overburden of tephras were observed to be conspicuous among various factors relating to the weathering of amorphous clay materials in Towada Ando soils.     

Phosphate fixation by ando soils different in their clay mineral composition

The phosphate fixation capacity at pH 4.5 and an equilibrium concentration of 250 mM phosphate was measured. The soil samples were divided into five groups according to their clay mineralogical composition. The first group soils contain opaline silica and allophanelike constituents, and some unidentified minerals, the second opaline silica and crystalline layer .i1icates, the third opaline silica and crystalline layer silicates with additional allophanelike constituents or aluminarich gel-like materials, the fourth allophanelike constituents, allophane and imogolite and the fifth crystalline layer silicates, allophanelike constituents and alumina-rich gel-like materials, plus some halloysite-like minerals, respectively. The first group soils had phosphate fixation capacities of 3,000 to 8,000, the second group soils 1,000 to 3,000, the third group loib 2,000 to 13,000, the fourth group soils 8,000 to 15,000 and the fifth group soil. 5,000 to 12,000 mg P₂O₅/100 g oven-dry soil, respectively. The fourth group soils in which allophane and imogolite predominated showed the highest phosphate fixation capacity.

The fractions which dissolved from almost all soil samples by treatments with 6% H₂O₂ Na₂S₂O₄-NaHCO₂-Na citrate and 2% Na₂CO₃ were estimated to have very high phosphate fixation capacities (8,000 to 19,000 mg P₂O₅/100 g dry-matter), and there was not much difference among the soil samples examined. Iron and aluminum combined with humus, allophanelike constituents, alumina-rich gel-like materials and halloysite-like minerals in addition to allophane and imogolite contribute to the phosphate fixation of Ando soils.     

Imogolite of Imogo-Layers in Kyushu

A distinct, brownish yellow soil layer often intervenes between dark colored layers in the profiles of Ando soil in Kyushu, particularly in central east and southern Kyushu. The layer is called “imogo” in the Hitoyoshi district and “akahoya” in the Miyazaki district. The soil is characterized by a very low bulk density such as 0.4, and bears glassy particles in abundance, which are colorless and shard-shaped. It often displays exchange-neutrality or exchange-alkalinity. Plant roots are very few in the layer, and most roots are observed to make a bend along the layer surface, from perpendicular to horizontal. It seems that the plant root has trouble intruding the layer, probably because of its special structure (1, 2).     

Implications of clay mineralogy to the weathering and chemistry of AP horizons of ando soils in Japan

The clay mineralogy of 22 samples of the Ap horizons of Ando soils was determined by a combination of methods. Of these samples, 15 did and 7 did not contain allophane and imogolite. Opaline silica was found in 4 samples, whereas aluminum—humus complexes, iron oxides and layer silicates were found in all samples. The presence of allophane and imogolite and the absence of opaline silica in a few Ap horizons was related to mixing of A₁ horizons and subsoils by cultivation and to lower supplies of organic matter relative to the amounts of aluminum released from volcanic ash by weathering. The contents of 2:1 and 2:1:1 layer silicates and their intergrades were larger in soils in which quartz predominated in fine fractions. It was inferred that aluminum bound with humus and in allophane-like constituents, rather than aluminum in allophane and imogolite, is important in reactions with phosphate and fluoride.     

Phosphate fractions in some tanzania soils

Inorganic-P fractions were determined in 17 soil profiles from eight soil orders widely occurring in Tanzania. Most of the inorganic-P fractions decreased with depth. Where soils were young, or calcareous, or the parent material rich in phosphorus-bearing minerals, Ca-P was the dominant inorganic-phosphorus fraction. Where the soils were highly weathered, Al-P and Fe-P were the dominant fractions.     

Fixed ammonium in some Bangladesh soils

Nitrogen is the most deficient element and the most limiting factor for crop production in Bangladesh. The total N content in Bangladesh soils ranges between 0.02 and 0.12% (Ahsan and Karim 1988). The low N content indicates the presence of a small organic N pool and suggests that inorganic N plays an important role as a N source for crops. Contribution of “fixed” or “nonexchangeable” NH₄ ⁺ to the N economy of soil has been reported for many tropical soils (Rodrigues 1954; Moore and Ayeke 1965; Dalal 1977; Sahrawat 1995). However, there are few reports on fixed NH₄ ⁺ status in Bangladesh. In the present study, therefore, attempts were made to collect data on fixed NH₄ ⁺ of some major soil series from the important physiographic units of Bangladesh.     

Urease activity in some Trinidad soils

The effects of urea concentration, soil moisture content, period of storage of soil samples, temperature and toluene on the urease activity of fifteen Trinidad soils were investigated. From the multiple regression analysis of clay content, organic carbon, CEC and amorphous Fe and Al and the urease activity of the soils, it was found that the urease activity in the presence of toluene was largely associated with the clay-organic matter complex whereas in the absence of toluene it was associated with the organic matter of the soils.     

Urea transformation in some tropical soils

The effects of incubation at 20°, 30° and 40°C and urea concentrations of 0, 50, 100 and 200 μg N/g soil on urea hydrolysis and nitrification were investigated in three Nigerian soils. At constant temperature urea hydrolysis and rate of NO₃^? accumulation increased with increasing rate of urea addition. Urea was rapidly hydrolyzed within 1 week of incubation. Nitrification in Apomu soil increased with increasing incubation temperature. Nitrification was slow in acid Nkpologu soil (pH 4.7). Texture, cation exchange capacity and C:N ratios of the soils were not related to urea hydrolysis or nitrification. Nitrite accumulation in these soils was insignificant. Soil pH was decreased by nitrification of hydrolyzed urea-N.     

Saccharides in some Japanese paddy soils

Monosaccharides released by acid hydrolysis from paddy field soil, from the light and the heavy fraction of soil, front some plant fragment were determined using automated anio-exchange chromatography.

Between 5 and 12 per cent of the organic carbon was present as saccharides.

The monosaccharide composition of the different soils was very similar, in spite of differences in the absolute amount of saccharides present. The amount of the various monosaccharide in the whole soil was found to be in the order glucose»xylose galactose, mannose, arabinose rhamnose ribose.

The monoccharide composition of the soils showed a marked contrast to that of the rice ra8ment, and partially decomposed plant remains taken from the soil. Glucose, xylose, arabi-the predominant saccharides in the rice fragments and the plant remains, while the amounts of galactose, mannose, rhamnose were negligibly small.

It was found that the proportion of galactose, mannose, rhamnose and ribose in the heavy fraction Of soil was greater than that of glucose, xylose, and arabinose

The present observation was in agreement with the view that soil sauharides comprised Pentoses originates in plant materials.

The molar ratio of xylose to mannose was calculated to show the characteristics of the mono-saccharide composition of soils and some plant muerials.     

Fixed ammonium determination in some clay soils

Abstract

We have shown that the traditional Kjeldahl method applied to clay soils of the Duero Basin (Spain) is not effective; so, it is necessary to add HC1 + HF to free trapped ammonium. This fixed ammonium has been measured by two methods which give significantly different results. The level of fixed ammonium in cultivated clay soils is relatively high (it ranges from 180 to 490 ppm). Fixed ammonium is significantly correlated to clay content and total inorganic nitrogen of the soil. A proposed method of analysis for total N is given.     

Sulphur mineralisation in some New Zealand soils

Summary An open incubation technique was used to measure S mineralisation in a range of New Zealand soils. For most of the soils studied, the release of S as sulphate was curvilinear with time, and during a 10-week incubation, the amounts of S mineralised ranged from less than 3 g S g^-1 soil to more than 26 g S g^-1 soil. The best predictor of mineralised S appeared to be the amount of C-bonded S in the soil (explaining 59% of the variation in mineralised S between soils). Examination of the soils after incubation also revealed that the bulk of the mineralised S was derived from the C-bonded S pool. Hydriodic acid-reducible forms of organic S appeared to make little contribution to mineralised S.Attempts were made to predict total potentially mineralisable S (S _o) from incubation data using an exponential equation and a reciprocal-plot technique. However, the dependence of estimated values of S _o on the length and temperature of incubation cast doubts on the validity of this approach.     

Trace elements in some Northern Nigerian soils

Abstract

The concentrations of the more‐or‐less strongly retained trace elements present in the root zone of some northern Nigerian soils were determined. The soils were chosen to represent some of the more extensively distributed soil orders under cultivation in the Nigerian savanna zone. Extraction by concentrated HNO₃ was used to determine the so‐called “total”; amount of retained Cu, Zn, Pb, Ni, Cd, and B in the soils. Aqueous solutions of the chelating agents, EDTA and DTPA, were used to extract the more weakly retained Cu, Zn, Pb, Ni, and Cd; whereas, hot water was used to extract the weakly retained B. The “total”; and the more‐weakly‐retained contents of these trace elements were significantly correlated with the amount of clay, silt, and the oxalate‐extractable oxyhydroxides present in the soils; whereas, only the weakly retained elements were significantly correlated with the content of organic matter in the soil. Both the “total”; concentrations and weakly‐retained Cu, Zn, and B were so low that deficiency problems may develop in these sandy soils if cultivated more intensively on a commercial scale without due precautions. The concentrations of the weakly‐retained toxic elements, Pb, Ni, and Cd, were low indicating that industrial pollution has not yet occurred.     

Mercury contents of some greek soils

Mercury contents were determined for horizons or layers of eleven profiles in agricutural areas and three in industrial areas of Greece.Mercury contents were determined for horizons or layers of eleven profiles in agricultural areas and three in industrial areas of Greece.Contents ranged from 25 to 98 ppb in profiles from agricultural areas. No trends in distribution within profiles or among kinds of soils were evident. Moreover, the levels are within the ranges found in uncontaminated soils elsewhere in the world. The contents are therefore considered to be normal background levels for soils of Greece. Amounts of mercury were positively correlated with cation exchange capacity but not with proportions of clay and organic matter.Contents of mercury reached a maximum of 325 ppb in upper layers and had a minimum of 45 ppb in the deeper parts of the profiles from the industrial areas. The greater amounts in the surface layers are attributed to enrichment through industrial activity. The maximum amounts are well above 150 ppb, a level proposed elsewhere as an upper limit for natural backgrounds.     

Potassium release by some delaware soils

Abstract

The A and B horizons of 29 Delaware soils were extensively cropped to sudan grass (Sorghum vulgare Pers. Piper) and corn (Zea mays L. Pioneer Brand Hybrid No. 3958) to evaluate the K release characteristics of these soils.

Various chemical analyses were made on these soils. The double acid North Carolina extractant (NCE) was good at predicting K uptake during the early stages of the experiment and was most sensitive with A horizon soils. However, this extractant was not suitable for predicting K uptake in the latter part of the experiment when nonexchangeable K was more important. Boiling IN HNO₃ was a good extractant in the latter part of the experiment when nonexchangeable K was being released and it also predicted K uptake from the B horizon well. Soils leached with 0.025M MgCl₂ and incubated 25 days to determine K released were also highly correlated with plant uptake.     

Chemical transformation of copper in some sludge-amended soils

In a laboratory incubation study, the periodic changes in different chemical fractions of copper (Cu) in three sludge-amended soil types (acidic sandy clay loam, neutral clay loam and alkaline clay loam) of varying soil reaction were monitored under field capacity and flooding moisture regime over 16 months. The water soluble and exchangeable fraction of Cu was very low (≤1% of total Cu) in all three soil types. At the end of incubation (16 months), the sodium acetate extractable (carbonate sorbed)- and residual-Cu fractions transformed into Fe-Mn oxide fraction, irrespective of moisture regime in all three soil types. However, the extent of transformation varied among soils.     

Fractionation of zinc in some New Zealand soils

Abstract

The amounts and forms of zinc in twenty surface soils from Canterbury and Southland, New Zealand were determined using a sequential fractionation scheme. Total soil zinc concentrations ranged from 38.1 mg#lbkg^‐1 to 113.8 mg#lbkg^‐1. Although the proportions of zinc found in individual fractions varied between soils, on average approximately 3% occurred as exchangeable zinc, 5% as organic‐bound zinc, 9%, 18%, 24% was associated with manganese, amorphous iron and crystalline iron oxides, respectively, and 40% was in the residual fraction. In a group of soils formed in greywacke alluvium or loess, exchangeable zinc was inversely related to soil pH. Within the same group of soils, those of similar age with greater concentrations of total and organic‐bound zinc were present in imperfectly‐ and poorly‐drained soils compared with well‐drained soils. Zinc extracted from the soils with a range of reagents used to assess ‘plant available’ zinc was correlated strongly with the concentrations of zinc present in the exchangeable and organic‐bound zinc fractions.     

Heavy metals in some soils of Western Georgia

The results of studying the background content of heavy metals in some soils of Western Georgia are considered. The total contents of chromium, copper, manganese, nickel, lead, and zinc were measured in samples from soil pits located in accordance with a 5-km square grid. The results of the laboratory investigations, which were processed using the statistical methods suggested by Salminen and Baitse, were the basis for the calculation of the background characteristics. Both methods are based on the use of medians that do not reflect the influence of anomalous heavy metal concentrations resulting from the anthropogenic impact, which cannot be avoided even when the locations of the soil pits are carefully chosen. The statistical methods used are compared; the advantage of the Salminen method is shown for soils that are not directly exposed to the influence of pollution sources. The background characteristics obtained are compared to the published ones. A conclusion is reached concerning the possible use of the Salminen method for the soils of Georgia.     

Non-symbiotic nitrogen fixation in some Hawaiian pasture soils

Evaluation of rates of non-symbiotic acetylene reduction in some pasture soils indicates the presence of certain bacteria capable of providing as much as 32 kg/ha/yr nitrogen to these soils. Variations in soil moisture content, especially as related to season, appear to have a profound effect on rates of acetylene reduction in soils tested. The facultative bacteria responsible for this fixation have been identified as species of the genera Klebsiella, Enterobacter and Achromobacter.     

Phosphorus status of some paddy soils in Bangladesh

Abstract

Phosphorus status of Bangladesh paddy soils covering the major paddy soil types was assessed in terms of parent materials and physiography. Total P concentration ranged from 172 to 604 mg kg^?1 in the topsoil and from 126 to 688 mg kg^?1 in the subsoil, and varied with the physiography to which the soils belonged. In most soils, the available P concentration was much higher for the topsoil than for the subsoil. The inorganic P concentration was higher than the organic P concentration, except for one soil series from the Old Himalayan Piedmont Plain, and was significantly and positively correlated with the total P concentration. Among the inorganic forms, only the concentration of Al-bound P showed a significant correlation with that of available P based on the Bray P-2 method in both topsoil and subsoil. In general, the P status was critically low in paddy soils of the terrace area. Normal growth of paddy rice in this area is expected to be difficult without application of P fertilizer.     

Carbonates in some soils of the Kamennaya Steppe

A comparative analysis of the conditions of formation and distribution of carbonates in the profiles of ordinary chernozems and meadow-chernozemic soils within the Kamennaya Steppe (Voronezh oblast) is given. On this basis, the approximate duration of the meadow stage of soil development is estimated. It is shown that the upper boundary of soil carbonates changes under the impact of forest shelterbelts.